1. Field of the Invention
The present invention relates to alternators driven by internal combustion engines. In particular, the present invention relates to a connection structure of a stator winding of an alternator to be mounted on an automotive vehicle, such as an automobile or a truck.
The entire content of the basic Japanese Patent Application from which the priority under the Convention is claimed in this application is hereby incorporated by reference into this application.
2. Description of the Related Art
In recent years, reduced sizes, increased outputs, and improved quality have been increasingly required of alternators. In order to obtain an increased output from an alternator reduced in size, it is important to distribute magnetic loading and electrical loading in a most appropriate manner and at a highest possible concentration within a limited volume.
The outputs of automotive alternators must be increased because of increasing vehicle loads while engine compartments become smaller, thereby reducing spaces for mounting the alternators. There are requirements to reduce the noise of the automotive alternators which operate all the time for supplying electricity, the noise becoming relatively large with respect to the engine noise which has been reduced in response to the requirements to reduce the noise generated toward the outside and the inside of the vehicle compartments. The automotive alternators, which operate all the time, are required to have a very high heat resistance because of their severe operating thermal condition in which the alternators are heated by a high Joule heat generated by the output current.
In order to reduce the size and increase the output of an alternator, the resistance of a stator winding must be reduced, the space factor of electrical conductors in magnetic circuits of the stator must be increased, and the bridge portions (bridge portions outside a stator core are called coil ends) of the stator winding must be set in order and be concentrated. Furthermore, the requirements for reduced noise and heat resistance, and the like must be complied with.
A structure for reducing the resistance of windings (heat loss), improving the space factor of electrical conductors, and lining up and concentrating coil ends was proposed disclosed in, for example, Japanese Patent No. 2927288, in which conductor segments formed substantially in a U-shape with short conductive wires having large cross-sections are used as strands of wire of the stator winding.
In an alternator of this type, the number of slots per pole and per phase tends to increase, that is, the alternator tends to have a plurality of sets of a three-phase alternating winding in order to comply with the requirements for reduced electrical and magnetic noise and high quality electricity supply, whereby the number of lead wires for the three-phase alternating winding is increased. When forming the three-phase alternating winding, a wiring process is necessary in which lead wires extending from the windings are drawn and are folded, and are connected. The laborious work in the wiring process is required to be alleviated. However, in the above Japanese Patent No. 2927288, the reduction of the load in the wiring process was not considered.
Therefore, the applicant of the present invention proposed a connection structure of lead wires of a stator winding in Japanese Patent Application No. 2000-011704 (a privately known but unpublished), for reducing load in a wiring process by alleviating the work for drawing and folding lead wires during a connection process of the stator winding.
FIG. 11 is a sectional view of a known automotive alternator proposed in Japanese Patent Application No. 2000-011704. FIG. 12 is a perspective view of a stator used in the known automotive alternator. FIG. 13 is a rear-end view explaining connections in one phase of a stator winding of the known automotive alternator. FIG. 14 is a perspective view of a terminal assembly for three-phase alternating connections in the stator of the known automotive. FIG. 15 is an illustration explaining a method of connection between a rectifier and the stator winding of the known automotive alternator. FIG. 16 is a block diagram of a circuit used in the known automotive alternator.
The automotive alternator shown in FIG. 11 includes a Lundell-type rotor 7 rotatably supported by a shaft 6 in a case 3 formed with aluminum front bracket 1 and rear bracket 2. A stator 8 is fixed to the inner wall of the case 3 so as to cover the rotor 7 at the periphery of the rotor 7.
The shaft 6 is rotatably supported by the front bracket 1 and the rear bracket 2. A pulley 4 is fixed to the shaft 6 at one end thereof, for transmitting the rotational torque of an engine to the shaft 6 via a belt (not shown).
Slip rings 9 for feeding current are fixed to the other end of the shaft 6. A pair of brushes 10 are received in a brush holder 11 disposed in the case 3. The pair of brushes 10 are held in contact with the slip rings 9 so as to slide thereon. A regulator 18 for regulating alternating voltage generated at the stator 8 is connected to a heat sink 17 coupled with the brush holder 11. Rectifiers 12 for rectifying alternating current generated at the stator 8 into direct current are mounted in the case 3, the rectifiers 12 being electrically connected to the stator 8.
The rotor 7 includes a rotor coil 13 for generating magnetic flux on passage of electric current, and a pair of pole cores 20 and 21 so as to cover the rotor coil 13, magnetic poles being formed in the pole cores 20 and 21 by the magnetic flux generated in the rotor coil 13. The pair of iron pole cores 20 and 21 include eight claw-shaped magnetic poles 22 and eight claw-shaped magnetic poles 23 around the peripheries of the pole cores 20 and 21, respectively, protruding therefrom and disposed at the same angular distance from each other in the circumferential directions of the respective pole cores 20 and 21. The pair of pole cores 20 and 21 are fastened to the shaft 6 facing each other such that the claw-shaped magnetic poles 22 and 23 intermesh. A fan unit 5 is fixed to the rotor 7 at each axial end thereof.
Intake openings 1a and 2a are formed in the front bracket 1 and the rear bracket 2, respectively, at each axial end face. Discharge openings 1b and two outlets 2b are formed in two outer circumferential shoulder portions of the front bracket 1 and the rear bracket 2, opposite the radial outside of the front-end and rear-end coil-end groups 16f and 16r of the stator winding 16.
In FIG. 12, the stator 8 includes a cylindrical stator core 15, made of laminated iron, provided with a plurality of slots 15a formed extending in the axial direction at a predetermined pitch in the circumferential direction, the stator winding 16 wound onto the stator core 15, and insulators 19 disposed in the slots 15a for electrically insulating the stator winding 16 from the stator core 15. The stator winding 16 includes twenty-four winding sub-portions in each of which one strand of wire 30 is bent back outside the slots 15a at both end surfaces of the stator core 15 and wound in a wave-shape so as to alternately occupy an inner layer and an outer layer in a slot depth direction within slots 15a at every sixth slot (equals a pitch of the magnetic poles). The stator core 15 is provided with ninety-six slots 15a at the same distance from each other so as to receive two sets of the three-phase alternating winding corresponding to the number of the magnetic poles which is 16. A long copper wire having a rectangular cross-section and coated with an insulating film, for example, is used as the strand of wire.
The winding configuration of a winding phase group 161 for a phase a is described below with reference to FIG. 13.
The winding phase group 161 for the phase a includes first to fourth winding sub-portions 31 to 34, each winding sub-portion being formed with one strand of wire 30. The first winding sub-portion 31 is formed in a manner such that one strand of wire 30 is wound in a wave-shape into every sixth slot from slot number 1 to 91 so as to alternately occupy a first position from the inner circumferential side (hereinafter, referred to as a first address) and a second position from the inner circumferential side (hereinafter, referred to as a second address) inside the slots 15a, and both ends of the strand of wire 30 are connected to each other, thereby forming the wave-shaped winding sub-portion in one turn. The second winding sub-portion 32 is formed in a manner such that one strand of wire 30 is wound in a wave-shape into every sixth slot from slot number 1 to 91 so as to alternately occupy the second address and the first address inside the slots 15a, and both ends of the strand of wire 30 are connected to each other, thereby forming the wave-shaped winding sub-portion in one turn. The third winding sub-portion 33 is formed in a manner such that one strand of wire 30 is wound in a wave-shape into every sixth slot from slot number 1 to 91 so as to alternately occupy a third position from the inner circumferential side (hereinafter, referred to as a third address) and a fourth position from the inner circumferential side (hereinafter, referred to as a fourth address) inside the slots 15a, and both ends of the strand of wire 30 are connected to each other, thereby forming the wave-shaped winding sub-portion in one turn. The fourth winding sub-portion 34 is formed in a manner such that one strand of wire 30 is wound in a wave-shape into every sixth slot from slot number 1 to 91 so as to alternately occupy the fourth address and the third address inside the slots 15a, and both ends of the strand of wire 30 are connected to each other, thereby forming the wave-shaped winding sub-portion in one turn. The strands of wire 30 are arranged to line up in a row of four strands within each slot 15a with the longitudinal direction of their rectangular cross-sections aligned in a radial direction.
Portions of the strands of wire 30 of the first and third winding sub-portions 31 and 33 extending from slot numbers 61 and 67 at an end surface of the stator core 15 are cut, respectively, and portions of the strands of wire 30 of the second and fourth winding sub-portions 32 and 34 extending from slot numbers 55 and 61 at the end surface of the stator core 15 are cut, respectively. Then, a cut end 31b of the first winding sub-portions 31 and a cut end 33a of the third winding sub-portion 33 are connected, a cut end 32b of the second winding sub-portions 32 and a cut end 34a of the fourth winding sub-portion 34 are connected, and a cut end 31a of the first winding sub-portions 31 and a cut end 32a of the second winding sub-portion 32 are connected. Thus, the winding phase group 161 in four turns for the phase a is formed with the first to fourth winding sub-portions 31 to 34 connected to each other in series.
Cut ends 33b and 34b of the third and fourth winding sub-portions 33 and 34, respectively, serve as an alternating-current-output lead wire Oa and a neutral-point lead wire Na for the phase a, respectively.
In the same manner, other five sets of four winding sub-portions are disposed in every sixth slot 15a. Thus, the winding phase groups 161 are formed for six phases, each set of four winding sub-portions being offset from the other by one slot.
In FIG. 12, two sets of a three-phase alternating winding constituting the stator winding 16 include twenty-four winding sub-portions connected in an alternating-current connection by using two three-phase-connection terminal-assemblies 100. In FIG. 14, each three-phase-connection terminal-assembly 100 includes a conductive neutral-point-connection member 101, three conductive bridge-connection members 102, and an insulative resin member 103 formed integrally with each other. The conductive neutral-point-connection member 101 is formed by bending a metallic bar made of copper or the like having a rectangular cross-section, and includes three connection tabs 101a and one neutral-point lead wire 101b. Each conductive bridge-connection member 102 is formed by bending a metallic bar made of copper or the like in a U-shape having a rectangular cross-section, and includes connection tabs 102a at the both ends thereof.
Two three-phase-connection terminal-assemblies 100 are disposed on the coil-end group 16r of the stator winding 16 in which the cut ends of the winding sub-portions for each phase are connected in a manner such that the cut ends 31b and 33a of the first and third winding sub-portions 31 and 33, respectively, are connected to each other by arc welding or the like, and the cut ends 32b and 34a of the second and fourth winding sub-portions 32 and 34, respectively, are connected to each other by arc welding or the like. The cut ends 31a and 32a of the first and second winding sub-portions 31 and 32 for each phase are led around, are folded, and are connected to the connection tabs 102a of each conductive bridge-connection members 102 by arc welding or the like. Thus, the winding phase groups 161 for the phase a, phase b, phase c, phase axe2x80x2, phase bxe2x80x2, and phase cxe2x80x2 are formed, the winding phase group 161 for each phase being configured with the first to fourth winding sub-portions 31 to 34. The cut end 34b of the fourth winding sub-portion 34 for each phase is led, is folded, and is connected to one of the connection tabs 101a of each conductive neutral-point-connection member 101 by arc welding or the like. Thus, a three-phase alternating winding is formed by connecting the winding phase groups 161 for the phases a, b and c in the alternating connection, and another three-phase alternating winding is formed by connecting the winding phase groups 161 for the phases axe2x80x2, bxe2x80x2 and cxe2x80x2 in the alternating connection. The cut ends 31a and 32a of the first and second winding sub-portions 31 and 32, respectively, function as the bridge-connection lead wires.
In the stator 8 thus configured, as shown in FIG. 12, two three-phase-connection terminal-assemblies 100 are disposed in the vicinity of the coil-end group 16r of the stator winding 16 wound onto the stator core 15. The alternating-current-output lead wires Oa, Ob, Oc, Oaxe2x80x2, Obxe2x80x2, and Ocxe2x80x2, and the neutral-point lead wires Nabc and Naxe2x80x2bxe2x80x2cxe2x80x2, which are the neutral-point lead wires 101b, of the two three-phase alternating windings of the stator winding 16 extend from the coil-end group 16r of the stator winding 16 in the axial direction.
In FIG. 15, a metallic connector 104 is fixed to the alternating-current-output lead wire Oa at the end thereof, is bent in the radial direction, and is connected to the rectifier 12. Other metallic connectors 104 are fixed to the alternating-current-output lead wires Ob, Oc, Oaxe2x80x2, Obxe2x80x2, and Ocxe2x80x2 and the neutral-point-connection lead wires Nabc and Naxe2x80x2bxe2x80x2cxe2x80x2 at the ends thereof, are bent in the radial directions, and are connected to the rectifier 12. Thus, as shown in FIG. 16, three phases each of the winding phase groups 161 are connected into the alternating connection to form the two sets of the three-phase alternating winding 160, and each of the three-phase alternating windings 160 is connected to its own rectifier 12. The direct current outputs of each rectifier 12 are combined by being connected in parallel. The neutral points of the three-phase alternating windings 160 are connected to direct current output terminals of the respective rectifier 12 via diodes 29.
In the known automotive alternator described above, the three-phase-connection terminal-assemblies 100 are disposed in the vicinity of the coil-end group 16r of the stator winding 16 and in a path of cooling air of the fan unit 5 between the coil-end group 16r and the rectifier 12, thereby increasing the wind resistance against the cooling air, whereby decreasing the volume of cooling air. Therefore, the rectifier 12 and the stator winding 16 cannot be cooled effectively, thereby increasing the temperature of the rectifier 12 and the stator winding 16. With the heat-up of the stator winding 16, the output thereof decreases. When the volume of cooling air is the same, wind noise increases by the three-phase-connection terminal-assemblies 100 which are disposed between the coil-end group 16f and the rectifier 12.
In the known alternator, the alternating-current-output lead wires Oa, Ob, Oc, Oaxe2x80x2, Obxe2x80x2, and Ocxe2x80x2 and the neutral-point-connection lead wires Nabc and Naxe2x80x2bxe2x80x2cxe2x80x2 of the three-phase alternating windings 160 are directly connected to the rectifier 12. Therefore, it is necessary to fix the metallic connectors 104 to the above alternating-current-output lead wires and the neutral-point-connection lead wires at the ends thereof, to bend the lead wires in the radial direction, and to couple the metallic connectors 104 with the rectifier 12, thereby increasing load in the connecting process.
The three-phase-connection terminal-assemblies 100, disposed close to the coil-end group 16r, reduce the space required for connection of the neutral-point lead wires and the bridge-connection lead wires with the conductive neutral-point-connection members 101 and the conductive bridge-connection members 102, respectively, thereby deteriorating the operation efficiency in the connecting process. The connecting operation, in which the neutral-point lead wires and the bridge-connection lead wires are led around, are folded, and are connected to the conductive neutral-point-connection members 101 and the conductive bridge-connection members 102, respectively, also deteriorates the efficiency in the connecting process.
Accordingly, it is an object of the present invention to provide a high-output alternator reduced in size in which wind resistance against the cooling air is reduced, the efficiency in cooling of a rectifier and a stator winding is improved, and the operation efficiency in a connecting process is improved by disposing conductive connecting-members at the rear side of a stator with respect to an end face of a fan unit in the axial direction of the stator so that the conductive connecting-members oppose the top of a coil-end group of the stator winding.
According to an aspect of the present invention, an alternator comprises: a stator including a cylindrical stator core provided with a plurality of slots extending in an axial direction of the stator, the plurality of slots being disposed in parallel to each other along the circumference of the stator, and a stator winding mounted in the plurality of slots of the cylindrical stator core, the stator winding including n-sets (n represents a natural number) of a three-phase alternating winding, each set of the three-phase alternating winding being constructed by connecting winding phase groups for three phases offset from each other by an electrical angle of 120 degrees into an alternating connection; a rotor enclosed by the cylindrical stator core; a fan unit mounted on the rotor; and a rectifier, wherein the stator winding comprises first wave-shaped windings and second wave-shaped windings, the first wave-shaped windings being composed of 3n first winding sub-portions each having one turn constructed by winding in a wave-shape a strand of wire so as to alternately occupy an inner layer and an outer layer in a slot-depth direction within the slots at every 3xc2x7nth slot, the first winding sub-portions being disposed at a pitch of one slot from each other, and the second wave-shaped windings being composed of 3n second winding sub-portions each having one turn constructed by winding in a wave-shape the strand of wire so as to alternately occupy the inner layer and the outer layer in the slot-depth direction within the slots at every 3xc2x7nth slot and so as to be inversely wound and offset by an electrical angle of 180 degrees relative to the first winding sub-portions, the second winding sub-portions being disposed at a pitch of one slot from each other, whereby m-pairs (m represents a natural number) of the first wave-shaped windings and the second wave-shaped windings are disposed so as to arrange alternately and in a row in-slot-received portions of the first winding sub-portions and in-slot-received portions of the second winding sub-portions in the slot-depth direction within each of said slots; wherein each set of the three-phase alternating winding is formed by connecting a plurality of lead wires to each other extending from the first winding sub-portions and the second winding sub-portions via a conductive relay member, and connecting into the alternating connection the three winding phase groups each composed of the first winding sub-portions and the second winding sub-portions which are mounted in every 3xc2x7nth slot; and wherein the conductive relay member opposes the top of a coil-end group of the stator winding across a gap therebetween.
The fan unit may be fixed to the rotor at at least one end thereof, the rectifier may be disposed at a side of the rotor to which the fan unit is fixed, the conductive relay member may be disposed at the side of the rotor to which the fan unit is fixed and be disposed opposite to the rotor with respect to an end face of the fan unit in the axial direction of the rotor, the plurality of lead wires may serve as alternating-output lead wires for the three-phase alternating winding, the conductive relay member may serve as conductive alternating-output-relay members having alternating-current-output-connection terminals extending inwardly in the radial direction of the rotor, and the alternating-output lead wires may be connected to the conductive alternating-output-relay members and be connected to the rectifier via the alternating-current-output-connection terminals.
The plurality of lead wires may serve as neutral-point-connection lead wires for the winding phase group, the conductive relay member may serve as a conductive neutral-point-relay member, and the neutral-point-connection lead wire for each phase may be integrally connected to the conductive neutral-point-relay member.
The conductive neutral-point-relay member may include a neutral-point-connection terminal extending inwardly in the radial direction of the stator, and the neutral-point-connection terminal may be connected to the rectifier.
The plurality of lead wires may serve as bridge-connection lead wires between the first winding sub-portions and the second winding sub-portions, the conductive relay member may serve as conductive bridge-connection-relay members, and the bridge-connection lead wires may be connected to the conductive bridge-connection-relay members, whereby the first winding sub-portions and the second winding sub-portions are bridge-connected.
The plurality of lead wires may extend in parallel to each other from the first winding sub-portions and the second winding sub-portions in the axial direction, and may be connected to the conductive relay member substantially at the same predetermined level as each other from an end face of the stator core.
The conductive relay member and an insulative resin member may be formed integrally with each other.
The stator may be formed so that the coil-end group of the stator winding does not overlap the fan unit in the radial direction.
The size of the conductive relay member in a radial direction of the stator may be not greater than the size of the coil-end group of the stator winding in the radial direction of the stator.
The strand of wire may be a continuous conductive wire, and the first winding sub-portion and the second winding sub-portion may form each of the first wave-shaped windings wound in one turn and each of the second wave-shaped windings wound in one turn, respectively.
The each pair of the first wave-shaped windings and the second wave-shaped windings may be formed with a winding assembly composed of a plurality of the first winding sub-portions and a plurality of the second winding sub-portions.